Semiconductor device and method

ABSTRACT

A vertical gate all around (VGAA) is provided. In embodiments, the VGAA has a nanowire with a first contact pad and a second contact pad. A gate electrode is utilized to help define a channel region within the nanowire. In additional embodiments multiple nanowires, multiple bottom contacts, multiple top contacts, and multiple gate contacts are utilized.

BACKGROUND

As the semiconductor industry has progressed into nanometer technology nodes in pursuit of higher device density, higher performance, and lower costs, challenges from both fabrication and design issues have resulted in the development of three-dimensional designs, such as a vertical gate all around (VGAA) transistor. A typical GAA transistor enables enhanced control of the charge carriers along the lengthwise direction through a complete encirclement of the channel region of a semiconductor nanowire by a gate dielectric and a gate electrode. The GAA transistor has a reduced short channel effect, because the channel region may be surrounded by the gate electrode so that an effect of the source/drain region on an electric field of the channel region may be reduced.

However, there are challenges to implementation of a VGAA. For example, the processes and methods utilized in complementary metal-oxide-semiconductor (CMOS) fabrication are not specifically tailored for the manufacture of VGAA transistors. As such, improvements are needed in the manufacturing processes in order to manufacture VGAA transistors.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the following detailed description when read with the accompanying figures. It is noted that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.

FIGS. 1A-1C illustrate a vertical gate all around transistor in accordance with some embodiments.

FIGS. 2A-3D illustrate embodiments that utilize multiple nanowires in accordance with some embodiments.

FIGS. 4-5 illustrate embodiments that utilize an array of nanowires in accordance with some embodiments.

FIGS. 6A-6F illustrate embodiments that utilize one or more bottom contacts in accordance with some embodiments.

FIGS. 7A-7E illustrate embodiments that utilize one or more top contacts in accordance with some embodiments.

FIGS. 8A-8C illustrate embodiments that utilize a single top contact in accordance with some embodiments.

FIGS. 9A-9F illustrate embodiments that utilize one or more gate contacts in accordance with some embodiments.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, or examples, for implementing different features of the provided subject matter. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly.

With reference now to FIGS. 1A-1C (with FIG. 1B being a cross-sectional view of FIG. 1A through line B-B′ and FIG. 1C being a cross-sectional view of FIG. 1A through line C-C′), there is illustrated a vertical gate all around (VGAA) transistor 100 with a substrate 101 with a first nanowire 111, a first contact pad 103, a gate dielectric 102, a gate electrode 105, a second contact pad 113, a first bottom contact 109, a first top contact 115, and a first gate contact 107. In an embodiment the substrate 101 comprises a semiconductor substrate (e.g., Si, SiGe, or SiGeB). In alternative embodiments, the substrate 101 comprises a silicon-on-insulator (SOI) structure. In some embodiments, the substrate 101 may comprise a compound semiconductor including silicon carbide, gallium arsenide, gallium phosphide, indium phosphide, indium arsenide, and indium antimonide; an alloy semiconductor including SiGe, SiGeSn, GeSn, GaAsP, AlInAs, AlGaAs, GaInAs, GaInP, and GaInAsP; or combinations thereof.

In some embodiments, the substrate 101 may comprise various doped regions (not individually illustrated) depending on design requirements (e.g., p-type substrate or n-type substrate). For example, the doped regions may be doped with p-type dopants, such as boron or BF₂; n-type dopants, such as phosphorus or arsenic; and/or combinations thereof. The doped regions may be configured for an n-type GAA transistor, or alternatively configured for a p-type GAA transistor. In some embodiments, the substrate 101 may include trench isolation regions 104 to isolate the various doped regions.

To help isolate the various doped region, trench isolation regions 104 may be formed. In an embodiment the trench isolation regions may be formed by initially applying a first photo-sensitive layer (not illustrated in FIGS. 1A-1C) is formed on the substrate 101 and is then patterned, forming openings in the first photo-sensitive layer. In some embodiments, the lithography processes include forming the first photo-sensitive layer by spin-on coating, exposing the first photo-sensitive layer using an exposure energy, such as ultraviolet (UV) light, and developing the exposed first photo-sensitive layer to form a patterned first photo-sensitive layer (with the openings) using a developer. In another example, the lithography process includes spin-on coating, soft baking, exposing, post-exposure baking, developing and hard baking. Alternatively, the lithography process to form the patterned first photoresist layer may alternatively use other techniques, such as e-beam lithography, maskless patterning or molecular printing.

Once the first photo-sensitive layer has been formed, the exposed substrate 101 is etched through the first photo-sensitive layer to form trenches (not separately illustrated in FIGS. 1A-1C) within the substrate 101. The first photo-sensitive layer is then removed. Next, a cleaning may be performed to remove a native oxide of the substrate 101. The cleaning may be performed using diluted hydrofluoric (DHF) acid.

The trenches may then be filled with a dielectric material, followed by a chemical mechanical polish (CMP) to form the trench isolation regions 104. The dielectric material may include silicon oxide. In some embodiments, other dielectric materials, such as silicon nitride, silicon oxynitride, fluoride-doped silicate glass (FSG), or a low-K dielectric material, may also be used. In an embodiment, the dielectric material may be formed using a high-density-plasma (HDP) CVD process, using silane (SiH₄) and oxygen (O₂) as reacting precursors. In other embodiment, the dielectric material may be formed using a sub-atmospheric CVD (SACVD) process or high aspect-ratio process (HARP), wherein process gases may comprise tetraethylorthosilicate (TEOS) and ozone (O₃). In yet other embodiment, the dielectric material may be formed using a spin-on-dielectric (SOD) process, such as hydrogen silsesquioxane (HSQ) or methyl silsesquioxane (MSQ).

After formation of the trench isolation regions 104, a second photo-sensitive layer (also not illustrated in FIGS. 1A-1C) is formed on the substrate 101 and is then patterned, forming openings in the second photo-sensitive layer to expose the substrate 101 and define areas for the formation of the first nanowire 111 from the substrate 101. In an embodiment the exposed substrate 101 is etched to form the first nanowire 111 from the substrate 101. The first nanowire 111 may be formed to have a first width W₁ of between about 1 nanometer and about 100 nanometers, such as about 10 nanometers, and a first height H₁ of between about 1 nanometer and about 1 micrometer, such as about 70 nanometers.

Once the first nanowire 111 has been formed, the second photo-sensitive layer is removed using a process such as ashing, whereby the temperature of the second photo-sensitive layer is increased until the second photo-sensitive layer thermally decomposes. Next, a cleaning may be performed to remove a native oxide of the substrate 101. The cleaning may be performed using diluted hydrofluoric (DHF) acid.

In some embodiments, a first source/drain region 112 (indicated in FIGS. 1B and 1C with a dashed line within the first nanowire 111) is formed by a first ion implantation process in the bottom portion of the first nanowire 111. In some embodiments, a metal silicide may be formed on the source region 212 (not shown).

The first source/drain region 112 includes an n-type dopant (such as phosphorous) when the GAA transistor is n-type or a p-type dopant (such as boron) when the GAA transistor is p-type. In some embodiments, the first source/drain region 112 formed by the ion implantation is further annealed for activation by an annealing process. The annealing process may be implemented right after the ion implantation may alternatively be implemented after the formation of other doped features for collective activation. In one embodiment, the annealing process includes rapid thermal annealing (RTA). In other embodiments, the annealing process alternatively includes laser annealing, spike annealing, millisecond anneal (MSA) or other suitable annealing technique.

Once the first source/drain region 112 has been formed, the first contact pad 103 is formed to provide electrical connection to the first source/drain region 112. In an embodiment the first contact pad 103 is formed of a conductive material such as aluminum, although other suitable materials, such as copper, tungsten, or the like, may alternatively be utilized. The first contact pad 103 may be formed using a process such as CVD or PVD, although other suitable materials and methods may alternatively be utilized. Once the material for the first contact pad 103 has been deposited, the material may be shaped into the first contact pad 103 using, e.g., one or more photolithographic masking and etching processes. Looking at FIG. 1A, in an embodiment the first contact pad 103 is formed with a second width W₂ of between about 20 nanometers and about 20 micrometers, such as about 485 nanometers, and a second length L₂ of between about 9 nanometers and about 20 micrometers, such as about 360 nanometers.

Once the first contact pad 105 has been formed, a first isolation region 106 is formed to isolate the substrate 101 and the subsequently formed gate electrode 105. In an embodiment the first isolation region 106 is formed over the first contact pad 103 and the substrate 101 and provides isolation function to and properly configures various features of the GAA transistor. In an embodiment the first isolation region 106 includes a dielectric material, such as silicon oxide. The first isolation region 106 may alternatively include other suitable dielectric material, such as silicon nitride, silicon oxynitride, carbon-doped silicon oxide, carbon-doped silicon nitride, or carbon-doped silicon oxynitride. In some embodiments, the forming of the dielectric material layer includes depositing a dielectric material using chemical vapor deposition (CVD), physical vapor deposition (PVD), or spin-on process, performing a CMP process to remove a portion of the dielectric material above the first nanowire 111, and etching back the dielectric material to the desired height to help define the first source/drain region 112.

Once the first isolation region 106 has been formed, the gate dielectric 102 and the gate electrode 105 surrounding a channel region 114 of the first nanowire 111 are formed. In an embodiment the gate electrode 105 is formed to surround the channel region 114 of the first nanowire 111 as well as to extend outwardly from the first nanowire 111 in order to allow for contact with the first gate contact 107.

In some embodiments, the gate dielectric 102 may include silicon oxide, silicon nitride, silicon oxynitride, or high-k dielectrics, such as metal oxides. Examples of metal oxides that may be used as high-k dielectrics include oxides of Li, Be, Mg, Ca, Sr, Sc, Y, Zr, Hf, Al, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and mixtures thereof. In the present embodiment, the gate dielectric 102 is a high-k dielectric layer with a thickness in the range of about 5 to 30 angstroms. The gate dielectric 102 may be formed using a suitable process such as atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), thermal oxidation, UV-ozone oxidation, or combinations thereof. The gate dielectric 102 may further comprise an interfacial layer (not shown) to reduce damage between the gate dielectric 102 and the channel region 114 of the first nanowire 111. The interfacial layer may comprise silicon oxide.

Once the gate dielectric 102 has been formed, the gate electrode 105 may be formed. In an embodiment the gate electrode 105 may be formed by initially forming a layer of metal (not separately illustrated in FIGS. 1A-1C) over the gate dielectric 102. In some embodiments, the layer of metal may comprise a single layer or a multilayer structure. In the present embodiment, the layer of metal may include a metal such as Al, Cu, W, Ti, Ta, TiN, TiAl, TiAlN, TaN, NiSi, CoSi, other conductive materials with a work function compatible with the substrate material, or combinations thereof. In the present embodiment, the gate electrode layer comprises a uniform thickness in the range of about 1 nanometer to about 20 nanometers. The layer of metal may be formed using a suitable process such as ALD, CVD, PVD, plating, or combinations thereof.

Once the layer of metal has been formed, the layer of metal may be patterned to separate the gate electrode 105 illustrated in FIGS. 1A-1C from other gate electrodes also formed from the layer of metal (not separately illustrated in FIGS. 1A-1C) by being selectively etched. In an embodiment the layer of metal may be patterned to form the gate electrode 105 by initially applying a third photo-sensitive layer (not separately illustrated in FIGS. 1A-1C) and then patterning the third photo-sensitive layer to expose a portion of the layer of metal that is desired to be removed and to cover a portion of the layer of metal that is desired to remain.

After patterning the third photo-sensitive layer to expose the layer of metal, the layer of metal is etched using the third photo-sensitive layer as a mask. In some embodiments, partially removing the exposed portion of the layer of metal is performed using a dry etch process at a temperature of about 10° C. to about 50° C., under a bias power of about 100 W to about 1000 W and a pressure of about 1 mTorr to about 40 mTorr, using Cl₂, HBr, BCl₃, NF₃, N₂, CF₄ and CH₂F₂ as an etching gas. Once the layer of metal has been patterned, the third photo-sensitive layer is removed using a process such as, e.g., ashing.

Once the layer of metal has been patterned to separate the gate electrode 105 from other gate electrodes, the layer of metal may also be patterned to define the channel region 114 of the first nanowire 111. In an embodiment the layer of metal may be patterned in this direction by initially forming a second isolation region 108 over the layer of metal. In an embodiment the second isolation region 108 includes a dielectric material, such as silicon oxide in the present example. The second isolation region 108 may alternatively include other suitable dielectric material, such as silicon nitride, silicon oxynitride, carbon-doped silicon oxide, carbon-doped silicon nitride, or carbon-doped silicon oxynitride. In some embodiments, the forming of the dielectric material layer includes depositing a dielectric material using CVD, PVD, or spin-on process, performing a CMP process to remove a portion of the dielectric material above the first nanowire 111, and etching back the dielectric material to a desired height to help define the channel region 114.

Once the second isolation feature 108 has been formed to help define the channel region 114, the second isolation region 108 may be used as a mask to help remove exposed portions of the layer of metal from over the first nanowire 111 and form the gate electrode 105 surrounding the channel region 114 of the first nanowire 111. In some embodiments, partially removing the exposed portion of the remaining layer of metal is performed using a dry etch process at a temperature of about 10° C. to about 50° C., under a bias power of about 100 W to about 1000 W and a pressure of about 1 mTorr to about 40 mTorr, using Cl₂, HBr, BCl₃, NF₃, N₂, CF₄ and CH₂F₂ as an etching gas. In an embodiment the gate electrode 105 may be formed to have a third width W₃ of between about 20 nanometers and about 20 micrometers, such as about 340 nanometers and a third length L₃ of between about 9 nanometers and about 20 micrometers, such as about 315 nanometers.

Once the channel region 114 has been defined by the gate electrode 105, a second source/drain region 116 may be formed in a portion of the first nanowire 111 uncovered by the gate electrode 105. In an embodiment, the second source/drain region 116 is formed by a second ion implantation process in the upper portion of the first nanowire 111. The second source/drain region 116 includes an n-type dopant (such as phosphorous) when the GAA transistor is n-type or a p-type dopant (such as boron) when the GAA transistor is p-type. In some embodiments, the second source/drain region 116 formed by the ion implantation is further annealed for activation by an annealing process. The annealing process is implemented after the ion implantation or is alternatively implemented after the formation of other doped features for collective activation. In one embodiment, the annealing process includes rapid thermal annealing (RTA). In other embodiments, the annealing process alternatively includes laser annealing, spike annealing, millisecond anneal (MSA) or other suitable annealing technique.

Once the gate electrode 105 and the second source/drain region 116 have been formed, a third isolation region 110 may be formed to isolate the second source/drain region 116 within the first nanowire 111. In an embodiment the third isolation region 110 includes a dielectric material, such as silicon oxide. The third isolation region 110 may alternatively include other suitable dielectric material, such as silicon nitride, silicon oxynitride, carbon-doped silicon oxide, carbon-doped silicon nitride, or carbon-doped silicon oxynitride. In some embodiments, the forming of the dielectric material includes depositing a dielectric material using, e.g., CVD, PVD, or a spin-on process, and then performing a CMP process to remove a portion of the dielectric material above the first nanowire 111.

Once the third isolation region 110 has been formed, the second contact pad 113 may be formed in electrical connection with the first nanowire 111. In an embodiment the second contact pad 113 is formed in order to provide electrical connection between the second source/drain region 116 within the first nanowire 111 and, e.g., the first top contact 115. In an embodiment the second contact pad 113 is formed of a conductive material such as aluminum, although other suitable materials, such as copper, tungsten, or the like, may alternatively be utilized. The second contact pad 113 may be formed using a process such as CVD or PVD, although other suitable materials and methods may alternatively be utilized. Once the material for the second contact pad 113 has been deposited, the material may be shaped into the second contact pad 113 using, e.g., a photolithographic masking and etching process. Looking at FIG. 1A, in an embodiment the second contact pad 113 is formed with a fourth width W₄ of between about 9 nanometers and about 20 micrometers, such as about 280 nanometers, and a fourth length L₄ of between about 9 nanometers and about 20 micrometers, such as about 260 nanometers.

After the second contact pad 113 has been formed, a fourth isolation region 117 may be formed to help isolate the second contact pad 113. In an embodiment the fourth isolation region 117 includes a dielectric material, such as silicon oxide in the present example. The fourth isolation region 117 may alternatively include other suitable dielectric material, such as silicon nitride, silicon oxynitride, carbon-doped silicon oxide, carbon-doped silicon nitride, or carbon-doped silicon oxynitride. In some embodiments, the forming of the dielectric material layer includes depositing a dielectric material using CVD, PVD, or a spin-on process. If desired, a CMP process may be utilized to planarize the fourth isolation region 117.

Once the VGAA transistor 100 has been formed, the first bottom contact 109, the first gate contact 107, and the first top contact 115 may be formed in order to electrically connect the first source/drain region 112, the second source/drain region 116, and the gate electrode 105. In an embodiment the first bottom contact 109, the first gate contact 107, and the first top contact 115 may be formed either together or separately by initially applying a fifth photo-sensitive material, patterning the fifth photo-sensitive material, and then removing portions of the fourth isolation region 117, the third isolation region 110, the second isolation region 108, and the first isolation region 106 to form openings and to expose portions of the second contact pad 113, the gate electrode 105, and the first contact pad 103.

Looking at FIG. 1A, in an embodiment the first bottom contact 109 may be formed to a fifth width W₅ of between about 1 nanometer and about 1 micrometer, such as about 40 nanometers, and a fifth length L₅ of between about 1 nanometer and about 20 micrometers, such as about 216 nanometers. Additionally, the first top contact 115 may be formed to a sixth width W₆ of between about 1 nanometer and about 20 micrometers, such as about 72 nanometers, and a sixth length L₆ of between about 1 nanometer and about 20 micrometers, such as about 26 nanometers. The first gate contact 107 may be formed to a seventh width W₇ of between about 1 nanometer and about 20 micrometers, such as about 50 nanometers and a seventh length L₇ of between about 1 nanometer and about 20 micrometers, such as about 50 nanometers.

Once the openings have been formed, the openings may be filled with a conductive material. In an embodiment the conductive material may be copper, although any suitable material may be used, and may be formed by initially forming a seed layer within the openings and then using a process such as plating in order to fill or overfill the openings with the conductive material. Once filled, any excess conductive material located outside of the openings may be removed using, e.g., a chemical mechanical polishing process.

By utilizing the first contact pad 103 and the second contact pad 113, the asymmetrical nature of the source/drain regions that can occur in the manufacturing process may be reduced or eliminated. By minimizing the variations between the source/drain regions, a more consistent device with better control may be manufactured.

FIGS. 2A-2D illustrate various embodiments which utilize a different number and placement of nanowires (e.g., the first nanowire 111, a second nanowire 201, and a third nanowire 203) in accordance with various embodiments. Looking first at FIG. 2A, FIG. 2A illustrates an embodiment in which, instead of the first nanowire 111, the second nanowire 201 and the third nanowire 203 are utilized. In an embodiment the second nanowire 201 and the third nanowire 203 are utilized within the VGAA transistor 100. In one embodiment the second nanowire 201 and the third nanowire 203 may be formed to similar dimensions and using similar process as the first nanowire 111 (described above with respect to FIGS. 1A-1C). However, the second nanowire 201 and the third nanowire 203 may alternatively be formed to different dimensions or using different process.

In an embodiment the second nanowire 201 and the third nanowire 203 are located such that they are not overlaid by the first top contact 115. For example, and as illustrated in FIG. 2A, the second nanowire 201 and the third nanowire 203 are located on opposing sides of the first top contact 115, and may be separated from each other by a first distance D₁ of less than about 20 micrometers, such as about 96 nanometers. However, any suitable distance may alternatively be utilized.

FIG. 2B illustrates another embodiment in which the first nanowire 111 is used in conjunction with the second nanowire 201 and the third nanowire 203. In this embodiment the first nanowire 111 is located beneath the first top contact 115 while the second nanowire 201 and the third nanowire 203 are located as described above with respect to FIG. 2A.

FIG. 2C illustrates another embodiment in which the second nanowire 201 and the third nanowire 203 are formed so as to be located at least partially beneath the first top contact 115. In this embodiment the second nanowire 201 and the third nanowire 203 may be arranged along a line that extends between the first gate contact 107 and the first bottom contact 109 (in the top down view).

FIG. 2D illustrates another embodiment in which the second nanowire 201 and the third nanowire 203 are arranged as described in FIG. 2C. In this embodiment, however, the first nanowire 111 is additionally included and is located beneath the first top contact 115. As illustrated, the first nanowire 111, the second nanowire 201, and the third nanowire 203 are all in a line with the first gate contact 107 and the first bottom contact 109.

FIGS. 3A-3D illustrate further embodiments in which the first nanowire 111, the second nanowire 201, and the third nanowire 203 are arranged in lines that are not parallel with the borders of the VGAA transistor 100. FIG. 3A illustrates an embodiment in which the positions of the second nanowire 201 and the third nanowire are rotated around the first top contact 115 such that the second nanowire 201 and the third nanowire 203 are at separate distances from the first gate contact 107. In the embodiment illustrated in FIG. 3A, the third nanowire 203 is located closer to the first gate contact 107 than the second nanowire 201.

FIG. 3B illustrates another embodiment similar to the embodiment illustrated in FIG. 3A. In this embodiment, however, the locations of the second nanowire 201 and the third nanowire 203 are rotated in an opposite direction than the embodiment discussed above with respect to FIG. 3A. Accordingly, in this embodiment the second nanowire 201 is located closer to the first gate contact 107 than the third nanowire 203.

FIGS. 3C and 3D illustrate further embodiments which the positions of the second nanowire 201 and the third nanowire 203 have been rotated as described above with respect to FIGS. 3A and 3B, respectively. In these embodiments, however, the second nanowire 201 and the third nanowire 203 are utilized in conjunction with the first nanowire 111, which is located as centered beneath the first top contact 115 as described above with respect to FIGS. 1A-1C.

FIG. 4 illustrates another embodiment in which an array of nanowires 401 is utilized. In this embodiment, instead of using one, two, or three nanowires (as described above with respect to FIGS. 2A-3D), the array of nanowires 401 may comprise a larger number of nanowires of between about 1 and about 1000000, such as about 96 nanowires. In the embodiment illustrated in FIG. 4, the array of nanowires 401 is arranged such that the individual nanowires are located in evenly spaced rows and columns. In an embodiment there are between about 1 row and about 1000 rows, such as about 12 rows and between about 1 column and about 1000 columns, such as about 8 columns.

In this embodiment the rows and columns may be evenly spaced apart from each other. For example, in an embodiment in which each one individual nanowire within the array of nanowires 401 has a diameter of between about 1 nanometer and about 100 nanometer, such as about 10 nanometer, the individual rows within the array of nanowires 401 may have a first pitch P₁ of less than about 20 micrometers, such as about 96 nanometers. Additionally, the individual columns within the array of nanowires 401 may have a second pitch P₂ of less than about 20 micrometers, such as about 96 nanometers.

FIG. 5 illustrates another embodiment that utilizes the array of nanowires 401. In this embodiment, however, instead of the plurality of nanowires being in evenly spaced rows and columns, the array of nanowires are arranged in rows and columns that are offset from each other. For example, in an embodiment in which the individual nanowires within the array of nanowires 401 have a diameter of about 10 nanometers, the rows may have a third pitch P₃ of less than about 20 micrometers, such as about 96 nanometers. However, adjacent rows may be offset from each other by a second distance D₂ of less than about 20 micrometers, such as about 96 nanometers.

By utilizing two or more nanowires, the overall VGAA transistor 100 can handle a larger current with less detrimental effects than the VGAA transistor 100 with only a single nanowire. As such, the VGAA transistor 100 can be utilized for a wide variety of applications. Additionally, by rotating the positions of the second nanowire 201 and the third nanowire 203, the benefits of using multiple nanowires may be achieved while also reducing the area needed for the placement of the multiple nanowires.

FIGS. 6A-6F illustrate further embodiments which utilize one or more bottom contacts (e.g., the first bottom contact 109, a second bottom contact 601, and a third bottom contact 603). Looking first at FIG. 6A, FIG. 6A illustrates the second bottom contact 601, instead of being located in line with the first top contact 115 and the gate electrode 105 as the first bottom contact 109 is in FIGS. 1A-1C, is located along a line that is at a right angle from a line that extends from the first top contact 115 and the first gate contact 107. In this embodiment the second bottom contact 601 may have an eight width W₈ of between about 1 nanometer and about 20 micrometers, such as about 240 nanometers, and a eighth length L₈ of between about 1 nanometer and about 20 micrometers, such as about 40 nanometers. The second bottom contact 601 may be formed using similar materials and similar processes as the first bottom contact 109 (illustrated and discussed above with respect to FIGS. 1A-1C).

FIG. 6B illustrates another embodiment in which the second bottom contact 601 is utilized in conjunction with the third bottom contact 603. In an embodiment the third bottom contact 603 is similar to the second bottom contact 601, but is located on an opposite side (in the top down view of FIG. 6B) of the first nanowire 111 than the second bottom contact 601.

FIG. 6C illustrates an embodiment in which the second bottom contact 601 is utilized in conjunction with the first bottom contact 109 and without the third bottom contact 603. In this embodiment the first bottom contact 109 is located as described above with respect to FIGS. 1A-1C, and the second bottom contact 601 is located as described above with respect to FIG. 6A.

FIG. 6D illustrates an embodiment in which the first bottom contact 109, the second bottom contact 601, and the third bottom contact 603 are all utilized together. In this embodiment the first bottom contact 109 is located as described above with respect to FIGS. 1A-1C, the second bottom contact 601 is located as described above with respect to FIG. 6A, and the third bottom contact 603 is located as described above with respect to FIG. 6B.

FIG. 6E illustrates an embodiment in which, instead of using the first bottom contact 109, the second bottom contact 601, and the third bottom contact 603 as separate structures, the first bottom contact 109, the second bottom contact 601, and the third bottom contact 603 are merged into a single U-shaped bottom contact 605. In this embodiment the U-shaped bottom contact 605 may have a first thickness T₁ of between about 1 nanometer and about 20 micrometers, such as about 40 nanometers. Additionally, the U-shaped bottom contact 605 may have a ninth width W₉ of between about 1 nanometer and about 20 micrometers, such as about 240 nanometers, and a ninth length L₉ of between about 3 nanometers, and about 20 micrometers, such as about 296 nanometers.

FIG. 6F illustrates an embodiment in which the, instead of using the first bottom contact 109, the second bottom contact 601, and the third bottom contact 603 separately, the first bottom contact 109 and the second bottom contact 601 are merged into a single L-shaped bottom contact 607. The single L-shaped bottom contact 607 may have the first thickness T₁, the ninth width W₉ and the ninth length L₉, although with only two legs instead of three.

FIGS. 7A-7E illustrate embodiments which utilize one or more top contacts (e.g., the first top contact 115, a second top contact 701, a third top contact 703, a fourth top contact 705, or a fifth top contact 710). Looking first at FIG. 7A, FIG. 7A illustrates an embodiment which uses the first top contact 115 along with the second top contact 701, wherein both the first top contact 115 and the second top contact 701 have a longitudinal axis that is parallel with a line extending between the first gate contact 107 and the first bottom contact 109. In this embodiment the first top contact 115 and the second top contact 701 may each have a tenth length L₁₀ of between about 1 nanometer and about 10 micrometers, such as about 20 nanometers, and a tenth width W₁₀ of between about 1 nanometer and about 20 micrometers, such as about 72 nanometers. Additionally, the first top contact 115 and the second top contact 701 may be spaced from each other a third distance D₃ of less than about 10 micrometers, such as about 60 nanometers.

FIG. 7B illustrates a plurality of top contacts, such as the first top contact 115, the second top contact 701, the third top contact 703, the fourth top contact 705, and the fifth top contact 710. Each of these contacts may have similar dimensions, such as the tenth width W₁₀ and the tenth length L₁₀, and may be spaced apart from each other by the third distance D₃.

FIG. 7C illustrates an embodiment in which the first top contact 115, instead of having a longitudinal axis that is parallel to a line extending between the first gate contact 107 and the first bottom contact 109, has a longitudinal axis that is perpendicular with the line extending between the first gate contact 107 and the first bottom contact 109. In this embodiment the first top contact 115 may have an eleventh width W₁₁ of between about 1 nanometer and about 20 micrometers, such as about 20 nanometers, and an eleventh length L₁₁ of between about 1 nanometer and about 20 micrometers, such as about 40 nanometers.

FIG. 7D illustrates an embodiment in which the first top contact 115 is oriented as described above with respect to FIG. 7C, and in which the second top contact 701 is additionally utilized. In this embodiment the second top contact 701 is oriented similar to the first top contact 115 (e.g., having a longitudinal axis perpendicular to the line extending between the first gate contact 107 and the first bottom contact 109). Additionally, the first top contact 115 and the second top contact 701 may be separated from each other by a fourth distance D₄ of less than about 20 micrometers, such as about 40 nanometers.

FIG. 7E illustrates an embodiment in which the third top contact 703 is utilized along with the second top contact 701 and the first top contact 115 wherein the third top contact 703 is oriented similar to the second top contact 701 (e.g., having a longitudinal axis parallel with a longitudinal axis of the first top contact 115). In this embodiment the first top contact 115, the second top contact 701, and the third top contact 703 are formed with a twelfth width W₁₂ of between about 1 nanometer and about 10 micrometers, such as about 20 nanometers, and a twelfth length L₁₂ of between about 1 nanometer and about 10 micrometers, such as about 240 nanometers. Additionally, the first top contact 115, the second top contact 701, and the third top contact 703 may be separated from each other by a fifth distance D₅ of less than about 20 micrometers, such as about 20 nanometers.

FIGS. 8A-8C illustrate embodiments that utilize a single top contact with differing shapes. FIG. 8A illustrates an embodiment in which a single L-shaped top contact 707 is utilized. In an embodiment the single L-shaped top contact 707 has a second thickness T₂ of between about 1 nanometer and about 20 micrometers, such as about 40 nanometers. Additionally, the single L-shaped top contact 707 may have a thirteenth width W₁₃ of between about 1 nanometer and about 20 micrometers, such as about 240 nanometers, and a thirteenth length L₁₃ of between about 1 nanometer and about 20 micrometers, such as about 240 nanometers.

FIG. 8B illustrates an embodiment in which a single U-shaped top contact 709 is utilized instead of the single L-shaped top contact 707 described above with respect to FIG. 8A. In an embodiment the single U-shaped contact 709 has the second thickness T₂, the thirteenth width W₁₃, and the thirteenth length L₁₃, although any suitable dimensions may alternatively be utilized.

FIG. 8C illustrates another embodiment which utilizes a single, squared shaped top contact 711 which, in the top down view of FIG. 8C, surrounds the first nanowire 111. In this embodiment the single, square shaped contact 711 has the second thickness T₂, the thirteenth width W₁₃, and the thirteenth length L₁₃, but has four sides instead of three sides (as in the embodiment illustrated in FIG. 8B) or two sides (as in the embodiments illustrated in FIG. 8A).

FIG. 9A illustrates an embodiment in which one or more gate contacts (e.g., the first gate contact 107, a second gate contact 901, or a third gate contact 903) is utilized. In the embodiment illustrated in FIG. 9A, the second gate contact 901 may be similar to the first gate contact 107 (described above with respect to FIGS. 1A-1C). The second gate contact 901, however, is not aligned with the first top contact 115 and the first bottom contact 109 (as the first gate contact 107 is aligned in FIGS. 1A-1C), but is instead aligned along a line that is perpendicular to a line that runs through the first top contact 115 and the first bottom contact 109.

Additionally, in this embodiment the gate electrode 105 may be sized to accommodate the changed position of the second gate contact 901. In an embodiment the gate electrode 105 has a fourteenth width W₁₄ of between about 1 nanometer and about 20 micrometers, such as about 480 nanometers, and a fourteenth length L₁₄ of between about 1 nanometer and about 20 micrometers, such as about 450 nanometers. However, any suitable size may alternatively be utilized.

FIG. 9B illustrates an embodiment in which a third gate contact 903 is utilized. In an embodiment the third gate contact 903 may be similar to the second gate contact 901, although located on an opposite side of the first nanowire 111 than the second gate contact 901. In this embodiment the gate electrode 105 may have the fourteenth width W₁₄ and the fourteenth length W₁₄, although extending in an opposite direction than the embodiment illustrated in FIG. 9A.

FIG. 9C illustrates an embodiment which utilizes the second gate contact 901 and the third gate contact 903. In an embodiment the second gate contact 901 is located as described above with respect to FIG. 9A and the third gate contact 903 is located as described above with respect to FIG. 9B. Additionally, in this embodiment the gate electrode 105 has a fifteenth width W₁₅ of between about 1 nanometer and about 20 micrometers, such as about 480 nanometers, and a fifteenth length L₁₅ of between about 3 nanometers and about 20 micrometers, such as about 600 nanometers.

FIG. 9D illustrates another embodiment in which the first gate contact 107 is utilized with the second gate contact 901. In this embodiment the first gate contact 107 is located as described above with respect to FIGS. 1A-1C, and the second gate contact 901 is located as described above with respect to FIG. 9A. Additionally, in this embodiment the gate electrode 105 has a sixteenth width W₁₆ of between about 2 nanometers and about 20 micrometers, such as about 600 nanometers, and a sixteenth length L₁₆ of between about 2 nanometers and about 20 micrometers, such as about 600 nanometers.

FIG. 9E illustrates an embodiment in which the first gate contact 107 is utilized with the third gate contact 903. In this embodiment the first gate contact 107 is located as described above with respect to FIGS. 1A-1C, and the third gate contact 903 is located as described above with respect to FIG. 9B. Additionally, in this embodiment the gate electrode 105 has the sixteenth width W₁₆ and the sixteenth length L₁₆.

FIG. 9F illustrates an embodiment in which the first gate contact 107 is utilized with the second gate contact 901 and the third gate contact 903. In this embodiment the first gate contact 107 is located as described above with respect to FIGS. 1A-1C, the second gate contact 901 is located as described above with respect to FIG. 9A, and the third gate contact 903 is located as described above with respect to FIG. 9B. Additionally, in this embodiment the gate electrode 105 has a seventeenth width W₁₇ of between about 2 nanometers and about 20 micrometers, such as about 480 nanometers, and a seventeenth length L₁₇ of between about 3 nanometers and about 20 micrometers, such as about 600 nanometers.

Additionally, as one of ordinary skill in the art will understand, the embodiments described herein are not intended to be isolated from each other. Rather, any embodiment may be utilized with any other embodiment described herein. For example, the embodiments illustrated herein with multiple nanowires may be utilized with the embodiments illustrated herein with multiple bottom contacts and multiple top contacts. Any suitable combination may be utilized, and all such combinations are fully intended to be included within the scope of the embodiments.

By utilizing the above described embodiments, the VGAA transistor 100 may be formed to suit a wide variety of different applications while keeping variations within the VGAA transistor 100 to a minimum. As such, by reducing variations, the output may be better controlled, and an overall better product may be manufactured.

In accordance with an embodiment, a semiconductor device comprising a first nanowire over a substrate, the first nanowire being perpendicular to the substrate and comprising a first source/drain region, a channel region over the first source/drain region, and a second source/drain region over the channel region is provided. A first contact pad is at least partially surrounding the first source/drain region. A gate electrode is at least partially surrounding the channel region. A second contact pad is in electrical connection with the second source/drain region.

In accordance with another embodiment, a semiconductor device comprising a first contact pad on a substrate and a second contact pad over the first contact pad is provided. A first nanowire extends between the first contact pad and the second contact pad and a gate electrode is surrounding a channel region of the first nanowire.

In accordance with yet another embodiment a method of manufacturing a semiconductor device comprising forming a first nanowire from a substrate is provided. A first contact pad is formed adjacent to a lower portion of the first nanowire. A gate electrode is formed adjacent to a middle portion of the first nanowire, and a second contact pad is formed adjacent to an upper portion of the first nanowire.

The foregoing outlines features of several embodiments so that those skilled in the art may better understand the aspects of the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure. 

What is claimed is:
 1. A semiconductor device comprising: a first nanowire over a semiconductor substrate, the first nanowire being perpendicular to and in physical contact with the semiconductor substrate and comprising a first source/drain region, a channel region over the first source/drain region, and a second source/drain region over the channel region; a first contact pad on the semiconductor substrate and at least partially surrounding the first source/drain region and covering at least a portion of a sidewall of the first nanowire; a gate electrode at least partially surrounding the channel region; a second contact pad in physical connection with a semiconductor section of the second source/drain region, wherein the second contact pad has a surface facing the semiconductor substrate, wherein the surface is planar from a first end of the second contact pad to a second end of the second contact pad opposite the first end and wherein the surface remains planar as the surface extends over the first nanowire; and a first bottom contact in electrical connection with the first contact pad, wherein the first bottom contact is a U-shaped contact.
 2. The semiconductor device of claim 1, further comprising a second nanowire, wherein the second nanowire comprises: a third source/drain region, wherein the first contact pad is at least partially surrounding the third source/drain region; and a fourth source/drain region, wherein the second contact pad is at least partially surrounding the fourth source/drain region.
 3. The semiconductor device of claim 2, further comprising a third nanowire, wherein the third nanowire comprises: a fifth source/drain region, wherein the first contact pad is at least partially surrounding the fifth source/drain region; and a sixth source/drain region, wherein the second contact pad is at least partially surrounding the sixth source/drain region.
 4. The semiconductor device of claim 1, further comprising: a first top contact in electrical connection with the second contact pad; and a gate contact in electrical connection with the gate electrode.
 5. The semiconductor device of claim 4, further comprising a second top contact in electrical connection with the second contact pad, wherein the second top contact is laterally separated from the first top contact.
 6. The semiconductor device of claim 4, wherein the first top contact is an L-shaped contact.
 7. The semiconductor device of claim 4, wherein the first top contact is a U-shaped contact.
 8. The semiconductor device of claim 4, wherein the first top contact is a square shaped contact.
 9. A semiconductor device comprising: a first contact pad on a semiconductor substrate; a second contact pad directly over the first contact pad, wherein the second contact pad has a first surface that is planar from a first end of the second contact pad to a second end of the second contact pad opposite the first end, wherein the first surface faces the semiconductor substrate; a first nanowire extending between the first contact pad and the first surface of the second contact pad and in physical contact with the semiconductor substrate, wherein the first surface is in physical contact with a semiconductor material of the first nanowire and remains planar as it extends over the first nanowire; a gate electrode surrounding a channel region of the first nanowire; and a contact in physical contact with the first contact pad, wherein the contact has either an “L” shape or a “U” shape.
 10. The semiconductor device of claim 9, wherein the first nanowire is part of an array of nanowires, wherein the array of nanowires has evenly spaced columns and rows.
 11. The semiconductor device of claim 9, wherein the first nanowire is part of an array of nanowires, wherein the array of nanowires has columns that are offset from each other.
 12. The semiconductor device of claim 9, further comprising: a first contact in electrical connection with the first contact pad; and a second contact in electrical connection with the first contact pad, the second contact being laterally separated from the first contact.
 13. The semiconductor device of claim 12, further comprising a third contact in electrical connection with the first contact pad, the third contact being laterally separated from the first contact and the second contact.
 14. The semiconductor device of claim 9, further comprising: a first gate contact in electrical connection with the gate electrode; and a second gate contact in electrical connection with the gate electrode, wherein the second gate contact is laterally separated from the first gate contact.
 15. The semiconductor device of claim 14, further comprising a third gate contact in electrical connection with the gate electrode, wherein the third gate contact is laterally separated from the first gate contact and the second gate contact.
 16. A method of manufacturing a semiconductor device, the method comprising: forming a first nanowire from a substrate; depositing a first contact pad adjacent to a lower portion of the first nanowire after the forming the first nanowire; forming a gate electrode adjacent to a middle portion of the first nanowire; forming a dielectric layer at least partially over the gate electrode and the first nanowire after the forming the gate electrode and after forming the first nanowire; planarizing the dielectric layer to form a planar surface between the dielectric layer and the first nanowire; forming a second contact pad adjacent to an upper portion of the first nanowire and in physical contact with the planar surface; and forming a first contact to the first contact pad, wherein the first contact is an L-shaped contact.
 17. The method of claim 16, further comprising forming a second nanowire from the substrate, wherein the forming the second contact pad further comprises forming the second contact pad adjacent to the second nanowire.
 18. The method of claim 17, further comprising forming an array of nanowires.
 19. The method of claim 16, further comprising forming a second nanowire from the substrate, wherein the depositing the first contact pad deposits the first contact pad adjacent to a lower portion of the second nanowire.
 20. The method of claim 19, wherein the forming the second contact pad forms the second contact pad adjacent to an upper portion of the second nanowire. 